Biomedical subjects

Johannes Kleinheinz

Publications and source records attributed to Johannes Kleinheinz.

18 recordsLinked to original sources

PubMed2007

The influence of lead thyroid collars on cephalometric landmark identification.

OBJECTIVE: To investigate whether the application of thyroid collars (TCs) affects cephalometric landmark identification. STUDY DESIGN: A randomized and observer-blinded diagnostic study with head films taken from 2 groups was undertaken, with 1 group wearing TCs during radiography (n = 100) and 1 group not wearing TCs (n = 100). The interobserver reproducibility of 15 landmarks was evaluated using 1-way analysis of variance and independent samples t test to compare the groups. RESULTS: The total mean error radius of the non-TC group (1.28 +/- 1.47 mm) was smaller (P < or = .001) than that of the TC group (1.57 +/- 1.58 mm). Three landmarks located on the hyoid bone and on the second and third cervical vertebrae were identified as the main confounding factors. CONCLUSIONS: Personal lead shielding of the thyroid gland affects landmark identification, but the overall clinical effect is negligible. Thyroid collars should be routinely applied during cephalometric radiography if cephalometric analyses are limited to structures above the second cervical vertebra.

Analysis of Variance↗

PubMed2006

Influence of treatment concept, velopharyngoplasty, gender and age on hypernasality in patients with cleft lip, alveolus and palate.

OBJECTIVES: The aim of this study was to analyse cleft patients for hypernasality following velopharyngoplasty. PATIENTS AND METHODS: 95 subjects (43 females, 52 males) with cleft lip, alveolus and palate (4 - 25 years old) were analysed. Forty-three patients were treated according to the current protocol of the Cleft Palate/Craniofacial Malformations Centre of the Department of Cranio-Maxillofacial Surgery in Muenster ('MS+' group) and 52 patients were treated elsewhere according to different protocols. In 19 of the 95 patients a velopharyngoplasty had been performed. Hypernasality was judged perceptually and nasalance data was measured objectively using the NasalView system. RESULTS: Patients of the 'MS+' group showed significantly better results concerning hypernasality and nasalance data. Assessment of hypernasality and nasalance measurement showed no significant differences between subjects following velopharyngoplasty and those who had not had this operation. Gender and age did not correlate with hypernasality either. CONCLUSION: A functionally orientated treatment with early closure of lip and palate ensures optimal velopharyngeal function, optimal oro-nasal balance of resonance, low hypernasality and excellent nasalance data.

Adolescent↗

PubMed2006

Melanotic neuroectodermal tumor of infancy: systematic review of the literature and presentation of a case.

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare, distinctive neoplasm of early infancy with rapid expansile growth and a high rate of recurrences. Most commonly the lesion affects the maxilla of infants during the first year of life, but it may also occur in the mandible, skull, brain, epididymis, and other rare locations. The origin of the tumor is the neural crest. The expansive, destructive, and rapid growth of MNTI and its effects on the surrounding tissues are the most obvious clinical features. Microscopically, large polygonal epithelioid cells resembling melanocytes, with variable deposits of melanin, and smaller neuroblast-like round cells characterize MNTI. Malignant transformation may occur. Since the first description in 1918, only 215 cases were reported up to the last extensive review in 1992. The present review supplements another 140 published cases of MNTI up to 2004, including an original case report. Clinical features, treatment alternatives, and follow-up are discussed.

Head and Neck Neoplasms↗

PubMed2006

Endothelial cell reaction on a biological material.

The successful clinical application of materials should involve detailed investigations on interaction between them and tissue with which they will contact. We examined herein the behavior of endothelial cells (ECs) on a collagen material, using histological and immunohistochemical methods. We used isolated human umbilical cord vein cells (HUVECs) identified by means of endothelial-specific antibodies. Cells were seeded in a standard density on a collagen membrane (Lycoll, Resorba, Nuernberg, Germany) and on gelatin-coated, control plastic surfaces, after two passages. These were then maintained for periods of 1, 7, or 14 days. The cells adhered, spread, and proliferated, and within 24 h started forming a subconfluent monolayer. We observed that the cultured cells expressed integrins (alpha5beta1 and alpha(v)beta3) and synthesized fibronectin. After 14 days, we could observe a confluent layer of ECs. We could conclude that the collagen material supported growth and attachment of endothelial cells. In addition, the attachment seemed to be most related to the fibronectin synthesized by the cells and to its highly expressed receptor (the alpha5beta1 integrin); even though this is not the only protein related to this adhesion, we observed that our cultured HUVECs did not synthesize vitronectin.

Biocompatible Materials↗

PubMed2006

Central giant cell granuloma of the jaws: a clinical, radiologic, and histopathologic study of 26 cases.

The clinical behavior of central giant cell granuloma (CGCG) of the jaws is variable and difficult to predict. Clinical data and follow-up information of 26 patients with CGCG were analyzed. Histologic features were correlated with the clinical course of the disease. In 16 patients the CGCGs were asymptomatic; 10 lesions presented with aggressive growth, pain, massive swelling, root resorption, cortical perforation, and/or recurrence. These patients were younger and the lesions were larger than in the nonaggressive group. The histomorphometric analysis proved a significant increase in large giant cells, fractional surface area, and mitotic activity in aggressive CGCG lesions. Immunohistologic investigation (Ki-67 and p53 stain) revealed no significant differences. After surgical treatment, 3 patients with aggressive lesions developed a recurrence. The data show that clinical and histomorphometric features may be reliable indicators for the differentiation between aggressive and nonaggressive CGCG. This should be accounted for to improve the individual planning of the treatment and follow-up.

Adolescent↗

PubMed2005

Comparison of laboratory and immediate diagnosis of coagulation for patients under oral anticoagulation therapy before dental surgery.

BACKGROUND: Dental surgery can be carried out on patients under oral anticoagulation therapy by using haemostyptic measures. The aim of the study was a comparative analysis of coagulation by laboratory methods and immediate patient diagnosis on the day of the planned procedure. METHODS: On the planned day of treatment, diagnoses were carried out on 298 patients for Prothrombin Time (PT), the International Normalised Ratio (INR), and Partial Thromboplastin Time (PTT). The decision to proceed with treatment was made with an INR < 4.0 according to laboratory results. RESULTS: Planned treatment did not go ahead in 2.7% of cases. Postoperatively, 14.8% resulted in secondary bleeding, but were able to be treated as out-patients. 1.7% had to be treated as in-patients. The average error between the immediate diagnosis and the laboratory method: 95% confidence interval was -5.8 +/- 15.2% for PT, -2.7 +/- 17.9 s for PTT and 0.23 +/- 0.80 for INR. The limits for concordance were 9.4 and -21.1% for PT, 15.2 and -20.5 s for PTT, and 1.03 and -0.57 for INR. CONCLUSION: This study showed a clinically acceptable concordance between laboratory and immediate diagnosis for INR. Concordance for PT and PTT did not meet clinical requirements. For patients under oral anticoagulation therapy, patient INR diagnosis enabled optimisation of the treatment procedure when planning dental surgery.

Adolescent↗

PubMed2005

Vascular basis of mucosal color.

BACKGROUND: Besides the color of the teeth the color of the alveolar gingiva plays a crucial role in esthetic rehabilitation in dento-alveolar treatment. Whereas nowadays the color of the teeth can be determined exactly and individually, the specific influence of the red color of the gingiva on treatment has not been assessed yet. The aim of this study was to evaluate the vascularization as the basis for gingival esthetics. METHODS: Standardized photographs of defined areas of the alveolar gingiva in operated and non-operated patients were taken and assigned to groups with same characteristics after color comparisons. In addition, histologic and immunohistologic analyses of gingival specimens were performed for qualitative and quantitative assessment of vessels and vascularization. Finally, colors and number of vessels were correlated. RESULTS: Our results demonstrated three different constellations of colors of the alveolar gingiva in healthy patients. The operated patients could not be grouped because of disparate depiction. There was a clear correlation between color and vessel number in the alveolar gingiva. CONCLUSION: Our investigations revealed the connections between vascularization and gingival color. Recommendations for specific change or even selection of colors based on the results cannot be given, but the importance of vascularly based incision lines was demonstrated.

Color↗

PubMed2005

Potential and limitations of cephalometric analysis of maxillofacial bone movement in the case of LeFort III-distraction.

BACKGROUND AND METHOD: The treatment of craniofacial deformities by means of distraction osteogenesis has become an established therapeutic procedure. Evaluation of the success of an operation is usually carried out via conventional cephalometry. Conventional forms of analysis seem problematic due to surgically-induced changes in the skull base. In this study we investigated the movement of the midface in the presence of a syndromerelated surgical indication employing two different types of analysis, namely those of Ricketts and Delaire. RESULTS: It seems that neither procedure is suitable for determining this type of bone movement conclusively. Comparing the two, the Delaire analysis possessed greater informative value in view of the altered geometry, and a combination of both procedures made more exact determination possible of the final position achieved.

Adolescent↗

PubMed2005

VEGF-activated angiogenesis during bone regeneration.

PURPOSE: The aim of this study was to investigate the influence of controlled release of recombinant human vascular endothelial growth factor (rhVEGF(165)) on angiogenesis and osteogenesis in a mandibular defect model. MATERIAL AND METHODS: A total of 56 rabbits were operated and bicortical holes were placed at the lower border of the mandible. The defects were filled with type-I collagen, with collagen complexed with 0.8 mug rhVEGF(165), or left without any filling. After 3, 7, 14, and 28 days, specimens were taken and histologic, histomorphometric, and immunohistologic analyses were carried out concerning number of vessels, cross-sectional area of vessels, and area and density of regenerated bone. RESULTS: Bone formation occurred in a typical centripetal direction and showed all stages of bone regeneration and maturation. New vessel formation took place in front of the osteogenic regeneration front. The number of vessels increased in all groups until day 14, followed by physiologic regression in the control groups as opposed to persisting high numbers in the study group. The area of newly formed bone showed no difference to the control group but the density of regenerated bone was significantly higher in the study group. CONCLUSION: Blood vessels are an important component of bone formation and maintenance and the bone tissue differentiation is related to the local presence of blood vessels. The activation of angiogenesis using rhVEGF(165) leads to more intensive angiogenesis and bone regeneration.

Animals↗

PubMed2005

Agressive fibromatosis involving the mandible--case report and review of the literature.

BACKGROUND: Aggressive fibromatosis (AF) involving the mandible is rare, and surgery is often complicated by a high recurrence rate. CASE REPORT: A 4-year-old boy was referred because of a fast growing painless mass which involved the entire left angle of the mandible. Excisional biopsy revealed AF, and local excision of the tumor was performed. Six months after surgery a recurrence was detected. The tumor was determined to be unresectable and the boy was treated with low-dose chemotherapy including methotrexate and vinblastine for 1 year. With combined chemotherapy and surgical debulking, mutilating surgical resection will be delayed as long as possible or until completion of facial growth. CONCLUSION: According to the literature, surgery is the most common treatment of AF in the head and neck region. However, particularly in children, alternative modes of therapy must be considered because of the high recurrence rate and to avoid mutilating operations.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2005

Biological and biomechanical evaluation of bone remodelling and implant stability after using an osteotome technique.

The influence of the osteotome technique on the osseointegration and biomechanical behaviour of cylinder implants (SLA, ITI was compared with conventional preparation of the implant site in an animal model. A total of 56 implants were placed in the cranial and caudal tibia condyle of six Gottinger minipigs. The implant site was prepared either by the conventional technique with drills (control group A) or by the osteotome technique (experimental group B). Resonance frequency measurements (RFMs) were made on each implant at the time of fixture placement and at the time of scarification. Half of the minipigs were sacrificed 7 days and 28 days after implant placement and the implants were removed with the surrounding bone. Bone tissue responses were evaluated by histological analysis and removal torque testing. For histological evaluation 30-50 microm-thick ground sections were examined. Biomechanical testing revealed a significantly higher stability of implants in the control group (A) than in the experimental group (B) (P = 0.004) at day 7. After 28 days implant stability in the control group remained significant higher (47%) than those of group B (P > 0.001). RFM demonstrated no significant difference between both groups and during the experimental course. Histological analysis demonstrated fractured trabeculae in peri-implant bone in the experimental group at day 7, while they were not posed at day 28. We conclude that the decreased implant stability by using the osteotome technique is based on microfractures in peri-implant bone.

Animals↗

PubMed2005

Interface reaction at dental implants inserted in condensed bone.

PURPOSE: The influence of the osteotome technique on the interface reaction of cylinder implants (SLA, ITI) was compared with the interface reaction of conventional implant insertion in an animal model. MATERIAL AND METHODS: A total of 64 implants were placed in the cranial and caudal tibia of 8 Göttinger minipigs. The implant site was prepared either by a conventional technique with drills (control group A) or by the osteotome technique (experimental group B). Bone tissue responses were evaluated by histomorphometry, fluorescence microscopy and scanning electron microscopy after 7 and 28 days of osseointegration. RESULTS: The average initial (7 days) bone-to-implant contact ratio was not statistically significantly different for the osteotome technique (35.88+/-2.94%) than for the control group (43.78+/-3.39%, P<0.095). After 28 days, the bone-to-implant contact ratio became statistically significantly higher when implants were inserted by conventional preparation (44.81+/-3.07% (group B), 63.47+/-4.87% (group A), P=0.003). Whereas fluorescence and immunhistologic examination revealed new bone formation with osteocalcin deposition directly at the implant surface in both groups, the extent of direct bone/implant contact was enhanced in conventionally prepared implant sites. SEM analysis confirmed an intimate bone to implant bond without fibrous tissue formation in places of direct contact at an ultrastructured level. CONCLUSION: Implant placement in conventionally prepared implantation sites is accompanied by an improved interface formation at an early stage of implantation.

Animals↗

PubMed2005

Incision design in implant dentistry based on vascularization of the mucosa.

OBJECTIVES: The delivery of an adequate amount of blood to the tissue capillaries for normal functioning of the organ is the primary purpose of the vascular system. Preserving the viability of the soft tissue segment depends on the soft tissue incision being properly designed in order to prevent impairment of the circulation. A knowledge of the course of the vessels as well as of their supply area are crucial to the decision of the incision. The aim of this study was to visualize the course of the arteries using different techniques, to perform macroscopic- and microscopic analyses, and to develop recommendations for incisions in implant dentistry. MATERIAL AND METHODS: The vascular systems of seven edentulous human cadavers were flushed out and filled with either red-colored rubber bond or Indian ink and formalin mixture. After fixation a macroscopic preparation was performed to reveal the course, distribution and supply area of the major vessels. In the area of the edentulous alveolar ridge specimens of the mucosa were taken and analyzed microscopically. RESULTS: The analyses revealed the major features of mucosal vascularization. The main course of the supplying arteries is from posterior to anterior, main vessels run parallel to the alveolar ridge in the vestibulum and the crestal area of the edentulous alveolar ridge is covered by a avascular zone with no anastomoses crossing the alveolar ridge. CONCLUSION: The results suggest midline incisions on the alveolar ridge, marginal incisions in dentated areas, releasing incisions only at the anterior border of the entire incision line, and avoidance of incisions crossing the alveolar ridge.

Cadaver↗

PubMed2004

Sustained release of doxycycline for the treatment of peri-implantitis: randomised controlled trial.

UNLABELLED: With the increased use of osseointegrated implants and with many implants functioning for a long time, the treatment of peri-implantitis has become important. Animal studies and clinical case reports have shown that the principle of guided bone regeneration can be applied to the surgical treatment of moderate to profound loss of bone around the implant, but we have found no published clinical studies. PATIENTS AND METHODS: Twenty-eight patients whose ages ranged from 25 to 78 years and who had a total of 48 peri-implant defects were examined at baseline (week 0) and after 18 weeks. This included the recording of bleeding on probing, pocket probing depths, and probing attachment levels at six sites for each tooth. For 2-18 weeks before week 0 all patients had been treated for peri-implantitis, including motivation, instruction in oral hygiene, and implant scaling with a hand plastic instrument. They were then randomly allocated to continue with this treatment or to have in addition mechanical debridement and local application of Atridox trade mark which slowly release doxycycline. RESULTS: Patients treated with Atridox trade mark showed a significantly greater gain in mean (S.D.) probing attachment levels than those not treated with Atridox. Only subjects treated with Atridox had a significant gain in mean bleeding on probing (P = 0.001). Application of the biodegradable sustained release device after initial periodontal treatment resulted in a significant gain in mean probing attachment levels in the Atridox trade mark group and a significant reduction in pocket probing depths. There was also a significant difference in mean probing attachment levels (0.6mm).

Adult↗

PubMed2004

Treatment of severe peri-implant bone loss using autogenous bone and a bioabsorbable polymer that delivered doxycycline (Atridox).

With an increase of the number of implants being inserted, it is inevitable that the number of cases of peri-implantitis with loss of bone will rise. We report a case in which an autogenous cancellous bone graft was placed into the peri-implant bone defect and given protection with a bioabsorbable polymer barrier (Atridox) that released doxycycline slowly.

Absorbable Implants↗

PubMed2004

Biomechanical and clinical implications of distraction osteogenesis in craniofacial surgery.

INTRODUCTION: Craniofacial distraction osteogenesis is an established surgical procedure to correct bony malformations. Force transduction through the osteotomized bone fragments elicits defined biological responses in the gap tissue, which determines the clinical success of the distraction treatment. OBJECTIVE: The purpose of this investigation was to evaluate clinically a new distraction protocol based on an analysis of the biological and biomechanical parameters executing direct effects on bone regeneration during distraction. STUDY DESIGN: A multistep distraction protocol was used in 39 patients and the clinical outcome was monitored postoperatively. RESULTS: All the distraction cases were successful with a single exception. Segmental displacements were stable clinically and radiologically. CONCLUSION: In order to improve the clinical success of distraction osteogenesis, individual treatment protocols are recommended.

Adolescent↗

PubMed2002

TCP is hardly resorbed and not osteoconductive in a non-loading calvarial model.

Tricalciumphosphate (TCP) has been used as a ceramic bone substitute material in the orthopedic field as well as in craniofacial surgery. Some controversies exist concerning the osteoconductive potential of this material in different implantation sites. This study was designed to evaluate the biological response of calvarial bone towards TCP granules under non-loading conditions to assess the potential of TCP as a biodegredable and osteoconductive bone substitue material for the cranial vault. Full-thickness non-critical size defects were made bilaterally in the calvaria of 21 adult Wistar rats. One side was filled by TCP granules, the contralateral side was left empty and used as a control. Animals were sacrified in defined time intervals up to 6 months. Bone regeneration was analyzed with special respect toward the micromorphological and microanalytical features of the material-bone interaction by electron microscopy and electron diffraction analysis. Histologic examination revealed no TCP degradation even after 6 months of implantation. In contrast, a nearly complete bone regeneration of control defects was found after 6 months. At all times TCP was surrounded by a thin fibrous layer without presence of osteoblasts and features of regular mineralization. As far as degradation and substitution are concerned, TCP is a less favourable material tinder conditions of non-loading.

Animals↗

PubMedDate not supplied

Implant dentistry at the focus of liability lawsuits.

PURPOSE: In recent years, the growing readiness on the part of dental patients to take legal action has resulted in an increasing number of medical liability lawsuits. The aim of this retrospective analysis was to highlight aspects of these lawsuits of special significance, to subject them to both qualitative and quantitative analysis, and to show how conflicts can be avoided. MATERIALS AND METHODS: Forty relevant court decisions from the year 1984 onwards were found in online databases and through direct inquiries at the courts. These were supplemented by 21 reports prepared by experts at the University of Muenster, Department of Dental Medicine, commissioned by courts in connection with ongoing lawsuits. Analysis was initially based on formal aspects of the cases and reports. It was later supplemented by differentiated assignment of the questions addressed by the courts to the expert consultants. The principles underlying the judgments as to the liability arising from the terms of the contract were also assigned to the expert consultants in a differentiated manner. RESULTS: The results revealed marked differences in the frequency of liability-prone aspects of treatment. While the majority of judgments referred to the obligation to take due care during the preparatory and treatment phases, infringement of the obligations to provide information and to keep records played more than a minor role. Moreover, 90% of all cases represented combined charges covering various aspects, including those related to consequential failings. DISCUSSION AND CONCLUSION: The detailed qualitative analysis of the grounds quoted and of the lines of reasoning can therefore be summed up in clearly defined recommendations aimed at helping the clinician avoid conflicts by observing the judicial requirements.

Compensation and Redress↗